Small vertebrate animals such as zebrafish are increasingly used at various stages of drug discovery process and becoming a useful and cost-effective alternative to mammalian models (such as rodents, dogs and pigs). Specific advantages of zebrafish, including a high degree of conservation to mammals, optically transparent organs, rapid development, and easy genetic manipulation process, make it one of the ideal models for high-throughput screening in living animals, which had previously been limited to invertebrates such as flies, worms and yeast. Moreover, zebrafish models have shown their desirable attributes on a huge scale of studies, including pharmaceutical development, genetic studies, and identification of the cellular targets of new compounds.
However, most studies involving organ-specific imaging of zebrafish require manual manipulation and orientation of fish larvae. Early screening methods for Zebrafish model were multi-well plate based, where fish embryos were manipulated and imaged inside each isolated compartment. Such screens have been used to study drug-induced toxicity to analyze hepatotoxicity, cardiotoxicity, and neurotoxicity. Advances in microscopy and image processing technique have also enabled behavioral assays on larvae within micro-wells. However, there are several limitations for such multi-well plate based methods. First, consistent long-term visualization of key organs in zebrafish is not possible within the wells, given their random orientation and fast movement. Second, even though the fishes can be anesthetized to minimize any significant body movement, the procedure is manual and laborious. Third, it is simply impossible to perform real-time organ specific activity monitoring during acute drug treatment using the multi-well based approach. These limitations have motivated development of newer tools that can enable handling the animals on other platforms.
Progress were made by some companies and academic labs. Pardo-Martin et al developed a platform capable of performing cellular-resolution imaging of zebrafish larvae at any orientation, which are automatically loaded larvae from multi-well plates and placed inside glass capillaries. While the system is mostly automated, this capillary-based platform only process very limited number of animals, and still requires anesthetic treatment to fishes, which may interfere with regular physiological functions, especially in the brain. In addition, there is no extra orthogonal dimension for coupling any drug treatment due to the complete encapsulation of fish larva in a capillary, and thus is not suitable for studies involve acute drug testing. An automated microfluidic device demonstrated by Chunhong Zheng et al aims to study drug dynamics in vivo using zebrafish model. However, this platform cannot be used to study specific organs with cellular level resolution due to the lack of orientation control.
The present invention seeks to provide a system which mitigates problems of existing systems for high-throughput studies involving small vertebrate animals such as zebrafish, or at least to provide an alternative to the public.